Andy, the fins you have now are ok. I have used the Gull Mew fins before, they are pretty popular in Japan. I use Bio fins- regular black. It is heavy but I don't notice it in the water. But they kick up a lot of silt if you are close to the bottom. I also have Tusa splits, which is better in preventing the silting. I don't think you will see any difference in your air consumption by switching to Bio fins. If you are comfortable with the fins you have now, I cannot see how you would use less air.